Sheet material detecting device

ABSTRACT

A sheet material detecting device for identifying the material of a sheet by utilizing an impact applied to the sheet comprises an impact applying means which is supported to be rotatable and shiftable toward the sheet, and applies an impact onto the sheet, an impact receiving means which is supported to be rotatable and shiftable in a state of being in contact-with the sheet onto which the impact has been applied, arranged opposite the impact applying means with a gap permitting the passage of the sheet in-between, and receives via the sheet the impact applied by the impact applying means onto the sheet, and a signal output unit which outputs a signal in response to the impact applied onto the sheet.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a signal output device. The inventionalso relates to a sheet material detecting device, more particularly toa sheet material detecting device which detects the type of a givensheet by applying an impact to the sheet.

2. Related Background Art

Some of the image formation devices which have come into use in recentyears, including copying machines, printers and facsimile machines, formimages on a wide variety of sheets differing in material, thickness andother attributes, including calendered paper, coated paper andtransparent resin film. Any such device, when it is to form an image onany type of these diverse sheets, has to match the operating conditionsincluding the feeding speed and the fixation temperature to theproperties of the sheet material, and conventional image formationdevices use a sheet material detecting device, integrated with orseparately disposed from them, for identifying the sheet material.

Such a sheet material detecting device is disclosed in, for instance, inthe U.S. Pat. No. 6,097,497. According to the technique proposed in thepatent, the sheet itself is marked in advance with a code consisting ofsome numeral or symbol and representing information on the sheet, asensor disposed in a printer reads the code, and the printer uses thecode information so read to optimize the printing mode (hereinafterreferred to as the marking system). However, such a marking system canbe of no use in detecting the material of any uncoded sheet.

Another sheet material detecting device which stops the feeding of asheet every time it distinguishes the material of the sheet, especiallyif it is built into a structure such as an image formation device, mayaffect the performance of the structure.

An object of the present invention is to provide a signal output device,method or the like which can supply information on sheet material evenif the sheet is not coded in advance.

Another object of the invention is to provide a sheet material detectingdevice capable of identifying the material of a sheet while feeding thesheet.

SUMMARY OF THE INVENTION

According to an aspect of the present invention, there is provided asheet material detecting device for identifying the material of a sheetby utilizing an impact applied to the sheet, comprising:

-   -   an impact applying means which is supported to be rotatable and        shiftable toward the sheet, and applies an impact onto the        sheet,    -   an impact receiving means which is supported to be rotatable and        shiftable in a state of being in contact with the sheet onto        which the impact has been applied, arranged opposite the impact        applying means with a gap permitting the passage of the sheet        in-between, and receives via the sheet the impact applied by the        impact applying means onto the sheet, and    -   a signal output unit which outputs a signal in response to the        impact applied onto the sheet.

The rotatable directions of the impact applying means and of the impactreceiving means preferably determine the carrying direction of thesheet. The sheet material detecting device preferably furthercomprising:

-   -   a first supporting means which supports the impact applying        means to be rotatable, shiftable toward the sheet and, after the        shift, returnable to its original position, and    -   a second supporting means which supports the impact receiving        means to be rotatable, shiftable in a state of being in contact        with the sheet onto which the impact has been applied and, after        the shift, returnable to its original position.

According to another aspect of the present invention, there is provideda sheet material detecting method using an impact applying means, animpact receiving means and a signal output unit, comprising:

-   -   an impact applying step at which the impact applying means        applies an impact onto the impact receiving means via a sheet,        and    -   a signal output step of outputting a signal in response to the        impact, and    -   a step of identifying the material of the sheet by comparing the        output signal with data stored in advance,    -   wherein:    -   the impact applying means is supported rotatably and shifts        toward the impact receiving means to apply an impact onto the        impact receiving means.

According to still another aspect of the present invention, there isprovided a sheet material detecting device which applies an impact ontoa sheet and identifies the material of the sheet according to the impacttransmitted via the sheet, comprising:

-   -   an impact applying portion for applying an impact onto the        sheet, and    -   an impact receiving portion for receiving the impact transmitted        via the sheet and performing detection, wherein:    -   the impact applying portion and the impact receiving portion        oppose each other and regulate the carrying direction of the        sheet.

The impact applying portion preferably comprises an impact applyingmeans which shifts toward the sheet and applies impact onto the sheetand a first supporting means which supports the impact applying means tobe rotatable, shiftable toward the sheet and, after the shift,returnable to its original position, and

-   -   the impact receiving portion comprises an impact receiving means        which is arranged opposite the impact applying means with a gap        permitting the passage of the sheet in-between and shifts in a        state of being in contact with the sheet onto which the impact        has been applied, and a second supporting means which supports        the impact receiving means to be rotatable and shiftable in a        state of being in contact with the sheet onto which the impact        has been applied and, after the shift, returns it to its        original position.

The impact applying means preferably has a spherical or cylindricalshape.

The impact receiving means preferably has a spherical or cylindricalshape.

The first supporting means and the second supporting preferably meansuse elasticity for returning the impact applying means and the impactreceiving means to their respective original positions.

The first supporting means and the second supporting means preferablyuse pneumatic pressure or hydraulic pressure for returning the impactapplying means and the impact receiving means to their respectiveoriginal positions.

The first supporting means preferably supports the impact applying meansvia the rotation shaft of the impact applying means and the secondsupporting means preferably supports the impact receiving means via therotation shaft of the impact receiving means.

According to a further aspect of the present invention, there isprovided a signal output device comprising:

-   -   an impact applying means for applying an impact onto a sheet,    -   an impact receiving means which, arranged opposite the impact        applying means, receives the impact applied to the impact        applying means via the sheet, and    -   a signal output unit which outputs a signal in response to the        impact applied onto the sheet,    -   wherein:    -   the impact applying means has an impact applying portion        supported to be rotatable and shiftable toward the sheet.

The present invention can contribute to simplifying the structure andreducing the cost by using the same configuration for the impactapplying portion and the impact receiving portion.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a schematic perspective view of the configuration of asheet material detecting device, which is a first preferred embodimentof the present invention;

FIG. 2 is a schematic section showing the configuration of the sheetmaterial detecting device;

FIG. 3 illustrates the sheet material detecting operation by the sheetmaterial detecting device;

FIGS. 4A, 4B and 4C respectively illustrate the voltage applied,impacting stroke and impacted side output in the sheet materialdetecting operation by the above sheet material detecting device;

FIGS. 5A, 5B, 5C and 5D illustrate a damper provided in the sheetmaterial detecting device; and

FIGS. 6A and 6B show a perspective view of the essential part of a sheetmaterial detecting device, which is a second preferred embodiment of theinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The principle of making it possible to detecting the sheet material byusing an impact will be explained below. The impact which an impactreceiving portion receives differs with the mechanical characteristicsof the sheet material including stiffness, Young's modulus andthickness. Therefore, the type of the sheet material is detected byutilizing these differences. The impact applied to the sheet material isdetected by a pressure sensor provided on either the impact applyingmeans side or the impact receiving portion side. Where the pressuresensor is a piezoelectric element such as PZT, the variation of thevoltage over time is the signal to be detected. The detected signal iscompared with data stored in advance, classified by the type of sheetmaterial, and the type of the fed sheet material is therebydistinguished.

First Embodiment

The configuration of a sheet material detecting device, which is a firstpreferred embodiment of the present invention will be described belowwith reference to FIG. 1 through FIG. 3. In FIG. 1, reference numeral154 denotes a impacting unit which is an impact applying portion to givevibration as an impact to a sheet 106, and 161, a impacted unit which isan impact receiving portion for detecting impact energy transmitted viathe sheet 106.

As shown in FIG. 2, the impacting unit 154 comprises a impacting unitcase 104, a impacting member 101 which is impact applying means tovibrate the sheet 106 by giving an impact to the sheet 106, apiezoelectric element 102 which is extended by the application of avoltage from a voltage applying circuit 105, a transmitting member 103which, disposed between the piezoelectric element 102 and the impactingmember 101 and on a side of the piezoelectric element 102 so as to bedisplaced by an equal distance toward the impacting member by the lengthof extension of the piezoelectric element, to transmit the extension ofthe piezoelectric element 102 to the impacting member 101, and a leafspring group 107 for holding the impacting member 101. A prescribed gapg1 is provided between the impacting member 101 and the transmittingmember 103.

The impacted unit 161 comprises a impacted unit case 111, a impactedmember 108 which is impact receiving means in contact with the sheet 106impacted by the application of the impact and subjected to thetransmission of the impact of the sheet 106, a piezoelectric element 110which outputs a voltage signal to a sense circuit 112 by beingcompressed by the received impact, a transmitting member 109 which,disposed between the impacted member 108 and the piezoelectric element110 and in a position on the side of the piezoelectric element 110toward the impacted member 108 to transmit to the piezoelectric element110 the impact received by the impacted member 108, and another leafspring group 107 for holding the impacted member 108. A prescribed gapg2 is provided between the impacted member 108 and the transmittingmember 109.

The impacted member 108 is so arranged opposite the impacting member 101so as to form between itself and the impacting member 101 a sheetpassage P, consisting of a gap g3, through which the sheet 106 weaveeither in light contact or not in contact with the members.

A voltage applied by the voltage applying circuit 105 and a signalsupplied from the sense circuit 112 according to a voltage signalentered from the impacted piezoelectric element 110 are entered into asheet material detecting portion 150, and the sheet material detectingportion 150 identifies the type of the sheet on the basis of thesesignals.

FIG. 3 illustrates the operation to detect the sheet 106 by the sheetmaterial detecting device in this embodiment of the invention. When thesheet 106 is carried to the sheet passage P in the direction of an arrow180 in FIG. 2, a voltage is applied from the voltage applying circuit105 to the piezoelectric element of the impacting unit (hereinafterreferred to as the impacting piezoelectric element) 102, and theimpacting piezoelectric element 102 is extended in the direction of thearrow by the inverse piezoelectric effect according to the level of thisvoltage. The length of extension of the impacting piezoelectric elementat a time per voltage application will be referred to as a “impactingstroke”. The displacement of the tip of the element due to thisextension is transmitted to the impacting member 101 via the motion ofthe transmitting member 103, and the impacting member 101 is pushedtoward the sheet to collide against the sheet 106. The displacement ofthe impacting piezoelectric element and of the transmitting member 103appended thereto toward the impacting member will be hereinafterreferred to as the “impacting displacement”. This impact is transmittedto the impacted member 108 of the impacted unit in contact with thesheet 106, and the impacted member 108 is thereby moved in the directionof an arrow 151, compressing via the transmitting member 109 in thedirection of an arrow 152 the impacted piezoelectric element(hereinafter referred to as the impacted piezoelectric element) 110 inthe direction of an arrow 153. The displacement due to the motion of theimpacted member 108 toward the impacted piezoelectric element 110 willbe hereinafter referred to as the “the impacted displacement”. Thelength of compression to which the impacted piezoelectric element issubjected at a time will be referred to as the “impacted stroke”. Thecompressed impacted piezoelectric element 110 is caused by apiezoelectric effect to generate a voltage signal according to themagnitude of the transmitted impact. The voltage signal is entered intothe sense circuit 112.

To add, after the impact ends, the impacting piezoelectric element 102and the impacted piezoelectric element 110 return to their respectiveoriginal dimensions, and the impacting member 101 and the impactedmember 108 return to their respective original positions.

The voltage from the voltage applying circuit 105 is applied a pluralityof times at prescribed intervals of time at a successively rising levelas shown in FIG. 4A. This voltage application a plurality of times givesrise to a plurality of consecutive impacting strokes. The impactingdisplacement due to the impacting strokes occurs in a quantity, at timeintervals and a number of times matching the level, time intervals andthe frequency of applications of the voltage as shown in FIG. 4B.Incidentally, the voltage signal applied by the voltage applying circuit105 is delivered to the sheet material detecting portion 150 to be usedas information for distinguishing the type of sheet material asdescribed earlier.

In order for the impacting displacement in one impacting stroke togenerate a impacted stroke via an intervening object, the quantity ofthe impacting displacement should be greater than the sum of the balanceof the subtraction of the thickness of the sheet 106 from the gap g3between the impacting member 101 and the impacted member 108, the gap g1between the transmitting member 103 and the impacting member 101, andthe gap g2 between the impacted member 108 and the transmitting member109. Namely the condition expressed in the following formula, where X isthe quantity of impacting displacement and T is the sheet thickness,should satisfied:g3−T+g1+g2<X

As long as the impacting displacement quantity X fails to satisfy thiscondition, the impacting displacement is not transmitted to theimpacting member 101, and the impacting member is not pushed toward thesheet or, even if the displacement is transmitted and the member ispushed, will not collide against the sheet; or even if it collides, thesheet will not transmit the impact to the impacted member 108; or evenif the impact is transmitted and the impacted member 108 a impacteddisplacement occurs, the impact will not reach the transmitting member109 and accordingly the impacted piezoelectric element 110 will not becompressed; namely no impacted stroke is generated. As a result, thevoltage signal from the impacted piezoelectric element 110 is zero.

As described above, a series of impacting strokes consists of strokesthe impacting displacement quantity X of which successively increasescorrespondingly to the rise in applied voltage. Therefore, if there is aimpacting stroke whose impacting displacement quantity X satisfies theformula above for the first time, every subsequent impacting stroke willsatisfy the formula and accordingly gives rise to a impacted stroke. Forinstance, the impacting stroke whose impacting displacement quantity Xis a in FIG. 4B does not satisfy the formula above, but those of b andmore in impacting displacement quantity do satisfy it. Therefore,impacted strokes arise matching only the impacting strokes of and afterwhat gives rise to the impacting displacement b, and they cause theimpacted piezoelectric element 110 to generate voltages. FIG. 4C showsvariations in this voltage shown by the impacted piezoelectric element110; no impacted stroke is generated matching any impacting stroke whoseimpacting displacement is less than a, and accordingly the voltagegenerated then by the impacted piezoelectric element 110 is zero.

A voltage signal outputted from the impacted piezoelectric element 110is inputted to the sense circuit 112, and a signal corresponding to thisvoltage signal is outputted from the sense circuit 112. The outputsignal is inputted to the sheet material detecting portion 150 asdescribed above. The sheet material detecting portion 150 determines thelevel of the voltage inputted from the voltage applying circuit 105 atwhich the output from the impacted piezoelectric element 110 begins tobe inputted. From the determined level, the thickness T of the sheet 106is detected. Also from the output of the impacted piezoelectric element110, the type of the sheet 106 as to material and other attribute can beidentified.

The impacting member 101 has a spherical, cylindrical or wheel-likeshape, and has a concave face matching the curved face it is opposed to.It is supported by accepting portions 401 for a damper 400 shown in FIG.5B, which are first supporting means, to be rotatable in the impactingunit case 104 as shown in FIG. 5A. The damper 400 consists of theaccepting portions 401, supports 402 for fixing the accepting portionsto the case 104, and two springs 403 and 404 whose two ends are fixed bythe supports and the case and disposed opposite each other with thesupports between them. The supports 402 and the impacting member 101held by them before impact are fixed in a position where the tensions ofthe two springs are balanced with each other as shown in FIG. 5B.

When impact is applied, as the impacting piezoelectric element 102extends to push out the impacting member 101, the supports 402 compressthe spring 403 toward the impacted unit 161 as shown in FIG. 5D and,while extending the spring 404 positioned toward the impactingpiezoelectric element 102, are deformed as shown in FIGS. 5A and 5D.When the impacting piezoelectric element 102 contracts to its originaldimensions after the impact is over, the extension of the spring 403 andthe contraction of the spring 404 return the supports 402 to theiroriginal positions, and along with that the impacting member 101 alsoreturns to its original position.

The impacted member 108 also has a spherical, cylindrical or wheel-likeshape, and held by accepting portions of a damper of the same structureas the damper 400, which is second supporting means, to be rotatable,shiftable and returnable to its original position within the impactedunit case 111.

Not only does the configuration described above contribute tosimplification but also, the moment at which an impact is applied to thesheet 106 in the gap g3, the two members function as rollers tofacilitate the movement of the sheet. For this reason, even while thesheet 106 is being carried, the type of the sheet can be identifiedwithout having to stop its motion. Thus, it is made possible to optimizethe imaging process according to the type of the sheet 106 whileadapting to a faster speed, resulting in higher image quality and powersaving. Furthermore, the use of the same configuration for the principalparts of the impacting unit 154 and the impacted unit 161 as describedabove makes possible simplification of the structure and a reduction incost. The configuration also helps broaden the choice of theinstallation space and facilitates high-speed paper feeding, becausethere is no obstruction to paper feeding.

Second Embodiment

FIG. 6A shows a perspective view of the essential part of a sheetmaterial detecting device, which is a second preferred embodiment of thepresent invention. In FIG. 6A, the same reference signs as in FIG. 2denote respectively the same or equivalent constituent parts.

In FIGS. 6A and 6B, reference numeral 501 denotes the rotation shaft ofthe cylindrically shaped impacting member 101, and the rotation shaft501 is provided with two springs 503 and 504 constituting part of adamper 500, which is first supporting means, in the moving direction ofthe impacting member 101 and disposed opposite each other as shown inFIG. 6B. The rotation shaft 501 before impact is fixed in a positionwhere the tensions of the two springs are balanced with each other.

When impact is applied, as the impacting piezoelectric element 102extends in the direction of the arrow 171 to push out the impactingmember 101, along with that the spring 503 toward the impactedpiezoelectric element is compressed and the spring 504 positioned towardthe impacting piezoelectric element 102 is extended. When the impactingpiezoelectric element 102 contracts to its original dimensions after theimpact is over, the compressed spring 503 is extended and the extendedspring 504 contracts to return to their original positions, and alongwith that the impacting member 101 also returns to its originalposition. Though not shown, the impacted member 108 is also held via arotation shaft 502 by a damper of a similar configuration to the damper500, which is second supporting means, to be shiftable in the directionof an arrow 172 toward the impacted piezoelectric element and to bereturnable to its original position. The directions of the shifting andreturning of the impacting member 101 and the impacted member 108 areindicated by arrows 173 and 174, respectively, in FIG. 6A.

In this embodiment, the impacting member 101 and the impacted member 108can rotate around the rotation shafts 501 and 502. In this structure,even the moment at which an impact is applied to the sheet 106 in thegap g3, the two members function as rollers to facilitate the movementof the sheet. For this reason, even while the sheet 106 is beingcarried, the type of the sheet can be identified without having to stopits motion.

Although the examples of springs shown in FIGS. 5B, 5D and 6B are coilsprings in the first and second embodiments, the usable means of dampingaccording to the invention are not limited to them, but pneumatic orhydraulic dampers can be used instead.

Third Embodiment

A method of detection according to the present invention will bedescribed with reference to FIG. 1, wherein reference numeral 154denotes an impact applying portion; 101, rotatably supported impactapplying means; 106, a sheet; and 161, an impact receiving portion.

The sheet 106 is a sheet that can be carried within a copying machine orany other image formation device, such as usual copying paper (plainpaper), calendered paper, coated paper or a transparent resin film.Detection of a sheet material in the context of the invention includesnot only the identification of the sheet material but also, forinstance, discrimination of sheets of the same material merely by thethickness.

First, the rotatably supported impact applying means 101 shifts towardthe sheet 106 and the impact receiving portion 161 carried along thesheet passage P in the direction of the arrow 180. Then, the impactapplying means applies an impact to the impact receiving means via thesheet. The impact applying means, though coming into contact with thesheet when applying the impact, immediately retracts to go out ofcontact with the sheet once it has applied the impact. As the impactapplying means is held in a rotatable state, it can apply an impact on asheet being carried, i.e. a sheet in a moving state, without obstructingthe motion of the sheet. Naturally, the wear of the impact applyingmeans due to contact with the sheet at the time of applying the impactcan be restrained.

It is preferable to hold not only the impact applying means but also theimpact receiving means rotatably. The impact can be applied by strikingthe member against the sheet, but the member continuously vibrating inprescribed cycles can as well be pressed against the impact receivingportion via the sheet.

It is also conceivable to compose the signal output device of the impactapplying means, the impact receiving means and a signal output unit, andto perform discrimination using a signal from the signal output deviceseparately. For instance, discrimination can be accomplished with acomputer externally connected to a copying machine. In anotherpreferable configuration, unnecessary noise and other elements can beremoved by using data from the signal output unit in which the impactapplying portion and the impact receiving portion are in direct contactwith each other with no intervening presence of a sheet.

This application claims priority from Japanese Patent Application No.2003-408275 filed Dec. 5, 2003, which is hereby incorporated byreference herein.

1. A sheet material detecting device for identifying the material of asheet by utilizing an impact applied to the sheet, comprising: an impactapplying means which is supported to be rotatable and shiftable towardthe sheet, and applies an impact onto the sheet, an impact receivingmeans which is supported to be rotatable and shiftable in a state ofbeing in contact with the sheet onto which the impact has been applied,arranged opposite the impact applying means with a gap permitting thepassage of said sheet in-between, and receives via the sheet the impactapplied by the impact applying means onto the sheet, and a signal outputunit which outputs a signal in response to the impact applied onto thesheet.
 2. The sheet material detecting device according to claim 1,wherein the rotatable directions of said impact applying means and ofsaid impact receiving means determine the carrying direction of saidsheet.
 3. The sheet material detecting device according to claim 2,further comprising: a first supporting means which supports said impactapplying means to be rotatable, shiftable toward the sheet and, afterthe shift, returnable to its original position, and a second supportingmeans which supports said impact receiving means to be rotatable,shiftable in a state of being in contact with the sheet onto which theimpact has been applied and, after the shift, returnable to its originalposition.
 4. The sheet material detecting device according to claim 3,wherein said impact applying means has a spherical or cylindrical shape.5. The sheet material detecting device according to claim 3, whereinsaid impact receiving means has a spherical or cylindrical shape.
 6. Thesheet material detecting device according to claim 3, wherein the firstsupporting means and the second supporting means use elasticity forreturning the impact applying means and the impact receiving means totheir respective original positions.
 7. The sheet material detectingdevice according to claim 3, wherein the first supporting means and thesecond supporting means use pneumatic pressure or hydraulic pressure forreturning the impact applying means and the impact receiving means totheir respective original positions.
 8. The sheet material detectingdevice according to claim 3, wherein the first supporting means supportsthe impact applying means via the rotation shaft of said impact applyingmeans and the second supporting means supports the impact receivingmeans via the rotation shaft of said impact receiving means.
 9. A sheetmaterial detecting method using an impact applying means, an impactreceiving means and a signal output unit, comprising: an impact applyingstep at which said impact applying means applies an impact onto saidimpact receiving means via a sheet, and a signal output step ofoutputting a signal in response to said impact, and a step ofidentifying the material of the sheet by comparing the output signalwith data stored in advance, wherein: said impact applying means issupported rotatably and shifts toward said impact receiving means toapply an impact onto said impact receiving means.
 10. A sheet materialdetecting device which applies an impact onto a sheet and identifies thematerial of the sheet according to the impact transmitted via the sheet,comprising: an impact applying portion for applying an impact onto thesheet, and an impact receiving portion for receiving the impacttransmitted via the sheet and performing detection, wherein: said impactapplying portion and said impact receiving portion oppose each other andregulate the carrying direction of said sheet.
 11. The sheet materialdetecting device according to claim 10, wherein: said impact applyingportion comprises an impact applying means which shifts toward saidsheet and applies impact onto the sheet and a first supporting meanswhich supports the impact applying means to be rotatable, shiftabletoward the sheet and, after the shift, returnable to its originalposition, and said impact receiving portion comprises an impactreceiving means which is arranged opposite the impact applying meanswith a gap permitting the passage of said sheet in-between and shifts ina state of being in contact with the sheet onto which the impact hasbeen applied, and a second supporting means which supports the impactreceiving means to be rotatable and shiftable in a state of being incontact with the sheet onto which the impact has been applied and, afterthe shift, returns it to its original position.
 12. The sheet materialdetecting device according to claim 11, wherein said impact applyingmeans has a spherical or cylindrical shape.
 13. The sheet materialdetecting device according to claim 11, wherein said impact receivingmeans has a spherical or cylindrical shape.
 14. The sheet materialdetecting device according to claim 11, wherein the first supportingmeans and the second supporting means use elasticity for returning theimpact applying means and the impact receiving means to their respectiveoriginal positions.
 15. The sheet material detecting device according toclaim 11, wherein the first supporting means and the second supportingmeans use pneumatic pressure or hydraulic pressure for returning theimpact applying means and the impact receiving means to their respectiveoriginal positions.
 16. The sheet material detecting device according toclaim 11, wherein the first supporting means supports the impactapplying means via the rotation shaft of said impact applying means andthe second supporting means supports the impact receiving means via therotation shaft of said impact receiving means.
 17. A signal outputdevice comprising: an impact applying means for applying an impact ontoa sheet, an impact receiving means which, arranged opposite the impactapplying means, receives the impact applied to the impact applying meansvia the sheet, and a signal output unit which outputs a signal inresponse to the impact applied onto the sheet, wherein: said impactapplying means has an impact applying portion supported to be rotatableand shiftable toward the sheet.